The refusal by Prince Charles to rule out marriage to Camilla Parker Bowles raises constitutional issues for both the Church of England and the monarchy.

Upon his succession to the throne Charles will become Supreme Governor of the Church, which has strict rules on the remarriage of divorcees.

Mrs Parker Bowles is divorced and her former husband Andrew is still alive - circumstances under which the Church would not normally conduct a marriage service.

The Prince of Wales is now a widower and he is free to re-marry

Bishop of Durham

Perhaps most controversially, the wife of a future king would automatically become a future queen.

Because of the rules governing the remarriage of divorcees, wedding Camilla would threaten to undermine Charles's moral authority as the head of the Church.

Religious obstacles

Camilla and Andrew Parker Bowles are divorced

There has been religious opposition to the idea of the couple becoming man and wife, although it is not universal.

More than half of England's bishops rejected the idea in a 1996 poll. And in 1997, the Archbishop of Canterbury, Dr George Carey, controversially warned that Charles's remarriage would throw the Church into crisis.

But in 1998, The Bishop of Durham, the Right Reverend Michael Turnbull, said Charles could remarry and still maintain the moral authority to become head of the Church.

Queen Camilla?

"Morally and ethically it would be more desirable for them to marry than for the situation to remain as it is," said the bishop.

"The Prince of Wales is, sadly, now a widower and he is free to re-marry."

Camilla Parker Bowles: Could become Charles's queen

The issue of divorcees being allowed to remarry in church is being discussed by members of the Anglican Church at their General Synod on Saturday.

But even if the Church were to change its practice, there is the question of whether the public will ever accept Mrs Parker Bowles as queen.

Under present constitutional law, she would assume this role as soon as Charles acceded to the throne.

Public opinion has shifted in favour of the couple marrying, although there is still doubt over whether Mrs Parker Bowles should become queen.

According to a newspaper poll last year, there would be widespread public support for the couple to wed.

Of the 1,200 people asked in a survey for the Mirror, 68% believed they should marry.

But 83% said Mrs Parker Bowles should never become queen.

The historical irony of the marriage debate is that the Church of England owes its very existence to Henry VIII's wish to divorce his first wife.